We will investigate the genetic, physiological and biochemical parameters of steroid regulation in gonad development, function and aging. Our approach is to isolate a large number of conditional mutants (either temperature sensitive or hormone sensitive) which are blocked in gonad development, function or sexual differentiation. These mutants will be microscopically characterized for their morphological and cellular defects. Simultaneously, mutants will be genetically analyzed to determine the number and types of genes that are involved in these complex events. Through genetic mapping we will be able to determine if these genes are located together on one chromosome or on many chromosomes. To correlate these mutants in molecular terms and to investigate molecular changes in aging animals, we will analyze both the wild type and the mutants for macromolecular steroid-binding activities. Simultaneous genetic, mutant and biochemical analyses should provide insights into the possible mechanisms by which steroids regulate gonad development, function and aging. The animals which we have chosen to accomplish this task is Caenorhabditis elegans, a free living soil nematode. This animal is ideal for genetic and biochemical analyses of sexual differentiation, gonad development and aging. It is small and easily cultured; it has a short lifespan; excellent genetics can be performed on this organism; many developmental mutants have been isolated; the animal is structurally simple; the anatomy and the development of the gonad is well characterized. Furthermore, this animal is already being used by other investigators as a model organism for aging research.